The founder of decentralized financial ecology

2. The decentralization of blockchain refers to the form of social relations and content generation formed in the process of blockchain development. It is a new network content proction process relative to "centralization"
blockchain is an important concept of bitcoin. It is essentially a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, which is used to verify the effectiveness of its information (anti-counterfeiting) and generate the next block
blockchain is unified in the whole network, so it is logically centralized. From the perspective of architecture, blockchain is based on peer-to-peer network, so it is decentralized. From the perspective of governance, blockchain makes it difficult for a few people to control the whole system through consensus algorithm, so it is decentralized.

3. Compared with the traditional centralized financial system, the decentralized financial platform has three advantages:
A. indivials with asset management needs do not need to trust any intermediaries, and the new trust is rebuilt on the machine and code
B. everyone has access, no one has central control
C. all protocols are open source, so anyone can cooperate on the protocols to build new financial procts and accelerate financial innovation under the network effect
defi is a relatively broad concept, including currency issuance, currency transaction, loan, asset transaction, investment and financing, etc
we regard the birth of BTC and other cryptocurrencies as the first stage of decentralized finance. However, the decentralization of currency issuance and storage only provides a point-to-point settlement solution, which is not enough to support the rich financial business. The rapid development of decentralized lending agreements in the past two years will have the opportunity to further open the financial system of the blockchain world and bring decentralized finance into the second stage<

the Xueshuo innovation blockchain Technology Workstation of Lianqiao ecation online is the only approved "blockchain Technology Specialty" pilot workstation of "smart learning workshop 2020 Xueshuo innovation workstation" launched by the school planning, construction and development center of the Ministry of ecation of China. Based on providing diversified growth paths for students, the professional station promotes the reform of the training mode of the combination of professional degree research, proction, learning and research, and constructs the applied and compound talent training system.

4. Hello, it's a great honor to be here to answer your question. The following are some of my views on this issue. If there are any mistakes, please point them out. Start all
and enter the column
almost every supporter of encryption start-ups has a trend, that is, to use the decentralized value of blockchain technology to sell their business fundamentals

in this paper, we will explain the differences between decentralized financial agreement business and traditional business:

we will mainly discuss two aspects:

1) what is the real meaning of defi

2) what are the types and main differences of defi platforms< Users of traditional financial systems often want to build a system that is easier to access, more transparent, lower transaction costs and less dependent on intermediaries. To build such a more equitable financial system, banks, loans and derivatives must undergo fundamental changes. In addition, a decentralized ecosystem, such as defi, is needed. It promotes P2P lending, eliminates centralized control, and provides users with financial freedom

recently, in the field of cryptocurrency, there are many discussions about defi. It provides financial services to the world: loans, derivatives and other procts. Moreover, the role of traditional financial intermediaries has weakened, or even failed to play a role. Proponents of a decentralized financial system see defi as a good alternative to traditional lending. Some have called it the future of borrowing

defi is built on public blockchains such as bitcoin network and Ethereum. It has become one of the "core drivers" on the Ethereum network. By using unlicensed distributed networks, the defi platform converts financial procts into untrusted protocols that can be accessed by anyone anywhere in the world. People who don't have an account in the bank can also use the defi solution to loan and borrow assets, as well as to trade with financial instruments

open source platforms provide users with great benefits, including transparency, cheap cross-border transactions, no credit checks and less censorship. Anyone can carry out financial activities because there is no geographical restriction<

the degree of decentralization of defi

in recent months, the introction of defi solutions has proliferated. They have different models and their degree of decentralization is also different. Compared with other models, some defi models have poor dispersion. This is because only a few of their components are decentralized, while the rest are still centrally controlled by the company

the establishment of agreement, non trust, price supply, determination of interest rate, provision of liquidity of margin call and start-up of margin call are the key components of defi agreement. They determine the degree of decentralization

if there are a large number of decentralized components, then the defi protocol is more decentralized than other models. Such a protocol will give users complete control over their digital assets and get rid of centralized control. So far, there is no single defi protocol that disperses all components

each defi protocol is assigned a category according to the number of distributed components:

centralized finance (cefi)

defi solutions are usually unmanaged, which means that users can control their funds and be responsible for their security. Instead, cefi is hosted. The central system is responsible for keeping the assets of users and ensuring the safety of users' funds

when it comes to loans or loans, users can't control any aspect of funds. The interest rate is determined by the central government, and the liquidity of margin call is provided by the central system or authorities. Cefi procts use centralized price supply, and it is also permitted to issue margin call. Thank you very much for your patience. If you have any help, please accept it. I wish you a happy life! thank you!

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6. Themis positioning centralization of digital asset hosting infrastructure is the world's first centralized digital asset hosting public chain, similar to Alipay's role in traditional escrow payment.
unlike traditional e-commerce escrow payment, Themis project uses the characteristics of blockchain and adopts group escrow mechanism to realize decentralized escrow service. Under such a mechanism, all parties can choose multiple third parties from a group of escrow service providers and mediate disputes by majority voting, thus ensuring fair exchange of digital assets
Themis does not rely on a single third party as a guarantee, so it reces the risk of collusion, denial of service and hacker attack, so that this fair and fair mechanism can promote the development of e-commerce, Global trade and smart contracts, and represents the development direction of innovative financial technology in real application scenarios.

7. JST coin is the ecological governance token of just, a decentralized financial system established by BoChang Tron. It was issued in May 2020 with a total supply of 99 million JST coins
the goal of just system is to establish a fair and decentralized financial system to provide stable currency lending and governance mechanism for all users in the world. This is a al token system. The first is usdj, which is a stable currency anchored to the US dollar at a ratio of 1:1. It is generated by mortgaging TRX on just's CDP lending platform. The second is the JST, which is part of the usdj monetary system
the system governance of just mainly depends on the holders of JST coins. On the one hand, the holders of JST coin can enjoy the income brought by the stable cost of usdj, on the other hand, the holders of JST coin also need to undertake the governance function of just system. The governance of just platform is mainly completed by the JST coin holders voting out effective proposals. Each JST coin holder can vote in the form of JST coin to select the contract he supports from all the smart contracts that modify the system parameters. After voting, the contract with the highest number of votes is the effective proposal. The effective proposal contract can obtain the system rights and complete the modification of the internal management variables of just system according to the established logic
JST coin founding team and its background:
JST coin has a vigorous elite team. 50% of the staff in the technical team are from Alibaba, Tencent, IBM and other world-class Internet companies, with rich experience in proct design and development. The financial analysis team of just system comes from several global investment banks, and the operation team has experienced in blockchain operation. At the same time, just system is also a strong supporter of wave field Tron ecology

8. How many people care about swap except when installing Linux? In fact, the adjustment of swap is very important to the performance of Linux server, especially web server. By adjusting swap, we can sometimes overcome the bottleneck of system performance and save the cost of system upgrade
as we all know, modern operating systems have implemented the technology of "virtual memory", which not only breaks through the limitation of physical memory in function, but also enables programs to manipulate the space larger than the actual physical memory. More importantly, "virtual memory" is a safety net to isolate each process, so that each process is not interfered by other programs

the function of swap space can be simply described as: when the physical memory of the system is not enough, a part of the space in the physical memory needs to be released for the current running program. The released space may come from some programs that haven't operated for a long time. The released space is temporarily saved in the swap space. When those programs want to run, they can restore the saved data from the swap to the memory. In this way, the system always swap when the physical memory is not enough

computer users often encounter this phenomenon. For example, when using Windows system, you can run multiple programs at the same time. When you switch to a program that you have ignored for a long time, you will hear the hard disk "crash". This is because the memory of this program is "stolen" by those programs that run frequently and put into the swap area. Therefore, once the program is placed on the front end, it will retrieve its own data from the swap area, put it into memory, and then run

it should be noted that not all the data exchanged from the physical memory will be put into swap (if so, swap will be overwhelmed), and a considerable part of the data will be directly exchanged to the file system. For example, some programs will open some files to read and write files (in fact, each program must open at least one file, that is, the running program itself). When it is necessary to exchange the memory space of these programs, it is not necessary to put the data of the file part into the swap space, but directly put it into the file. If it is a read file operation, the memory data will be released directly without exchange, because it can be directly recovered from the file system next time; If you are writing a file, you only need to save the changed data to the file for recovery. However, the data of objects generated by malloc and new functions are different. They need swap space because they have no corresponding "reserved" files in the file system, so they are called "anonymous" memory data. This kind of data also includes some state and variable data in the stack. Therefore, swap space is the exchange space of "anonymous" data<

break through the limitation of 128M swap

it is often seen in some Linux (Chinese version) installation manuals that the swap space cannot exceed 128M. Why is there such a saying? Before explaining the origin of "128M", let's give an answer to the question: there is no 128M limit at all! Now the limit is 2G

swap space is paginated, and the size of each page is the same as that of memory page, which facilitates data exchange between swap space and memory. When the old version of Linux implemented swap space, the first page of swap space was used as a "bitmap" of all swap space pages. That is to say, every bit of the first page corresponds to a page of swap space. If this bit is 1, it means that the page swap is available; If it is 0, it means that the page is a bad block and cannot be used. So the first swap mapping bit should be 0, because the first swap page is the mapping page. In addition, the last 10 mapping bits are also occupied to represent the version of swap (the original version was swap)_ The current version is swap space 2). Then, if the size of a page is s, this implementation of swap can manage a total of "8 * (s - 10) - 1" swap pages. For the i386 system, if s = 4096, the total space size is 133890048. If 1 MB = 2 ^ 20 byte, the space size is exactly 128M

the reason to manage the swap space in this way is to prevent bad blocks in the swap space. If the system detects a bad block in the swap, it marks 0 on the corresponding bit map to indicate that the page is not available. In this way, when using swap, it is not necessary to use bad blocks, which will cause system errors< Now system designers think that: the quality of hard disk is very good, and there are few bad blocks

2. Even if there are, there are not many. You only need to list out the bad blocks, and you don't need to create a mapping for each page

3. If there are many bad blocks, this hard disk should not be used as swap space

as a result, the current Linux system cancels the bit mapping method, which means the 128M limit is removed. Direct access with address, limited to 2G

the impact of swap configuration on performance

allocating too much swap space will waste disk space, and if there is too little swap space, errors will occur

if the physical memory of the system is used up, the system will run very slowly, but it can still run; If you run out of swap space, an error will occur. For example, a web server can generate multiple service processes (or threads) according to the number of different requests. If the swap space is used up, the service process cannot be started, and the error of "application is out of memory" usually occurs, which may cause the deadlock of the service process in serious cases. Therefore, the allocation of swap space is very important

generally, the swap space should be greater than or equal to the size of physical memory, and the minimum size should not be less than 64M. Generally, the size of swap space should be 2-2.5 times of physical memory. But according to different applications, there should be different configurations: if it is a small desktop system, it only needs a small swap space, while a large server system needs different sizes of swap space depending on the situation. Especially for database server and web server, with the increase of access, the requirement for swap space will also increase. For specific configuration, please refer to the description of each server proct

in addition, the number of swap partitions has a great impact on performance. Because the operation of swap is the operation of disk IO, if there are multiple swap areas, the allocation of swap space will operate on all swaps in turn, which will greatly balance the load of IO and accelerate the speed of swap. If there is only one exchange area, all the exchange operations will make the exchange area very busy, making the system in a waiting state most of the time, and the efficiency is very low. Using the performance monitoring tool, you will find that the CPU is not very busy at this time, but the system is slow. This shows that the bottleneck is Io, and it can not be solved by improving the speed of CPU
system performance monitoring

the allocation of swap space is very important, but the system runtime performance monitoring is more valuable. Through the performance monitoring tool, we can check the performance indicators of the system and find the bottleneck of the system performance. This article only introces some commands and uses related to swap under Solaris

the most common command is the vmstat command (there are some commands under most UNIX platforms), which can view most performance indicators

for example:
# vmstat 3
procs memory swap IO system CPU
R BW swpd free buff cache si so Bi Bo in CS US sy ID
0 000 93880 3304 19372 00 102 131 1000 99
0 000 93880 3304 19372 00 109 800 100
0 000 93880 3304 19372 00 00 112 600 100
...

command description :
the parameters after vmstat specify the time interval for performance metric capture. 3 means capture every three seconds. The first line of data does not need to be looked at. It has no value. It only reflects the average performance since startup. Starting from the second line, reflect the system performance index every three seconds. These performance indicators related to swap include the following items:

W
under procs, which indicates the number of processes that need to release memory and swap out at present (within three seconds)< The swpd in

memory
indicates the size of the swap space used

Si in swap, so
Si represents the total amount of swap in per second (within three seconds), in Kbytes; So represents the total amount of swap out memory per second (within three seconds), in Kbytes
the larger the number of indicators above, the busier the system is. The busy degree of the system represented by these indicators is related to the specific configuration of the system. The system administrator should write down the values of these indicators when the system is running normally, and then compare them when the system has problems, so that the problems can be found quickly, and the standard indicators of the normal operation of the system can be formulated for the use of performance monitoring

in addition, using swapon-s can also simply view the current usage of swap resources. For example:
# swap - s
file type size used priority
/ dev / hda9 partition 3614200 3

it is convenient to see the size of used and unused resources in swap space

the swap load should be kept below 30% to ensure the good performance of the system<

system commands about swap operation

increase swap space in the following steps:
1) become a super user
$Su - root

2) create swap file
# DD if = / dev / zero of = swap file BS = 1024 count = 65536

create a swap file with continuous space

3) activate swap file
; / usr / SBIN / swap on swap file

swap file refers to the swap file created in the previous step. 4) Now the new swap file has worked, but after the system is restarted, the previous steps will not be remembered. Therefore, the name of the file and the swap type should be recorded in the / etc / fstab file, such as:
/ path / swapfile none swap SW, PRI = 300

5) to check whether the swap file is added with
/ usr / SBIN / swapon - s


to delete the rendant swap space
1) become a super user

2) use the swapoff command to reclaim the swap space
; / usr / SBIN / swapoff swapfile

3) edit the / etc / fstab file to remove the entity of the swap file

4) reclaim this file from the file system< Of course, if the swap space is not a file, but a partition, you need to create a new file system and then attach it to the original file system.